Development of an index for the assessment of welfare of finishing pigs from farm to slaughter based on expert opinion

For pigs, the day of slaughter involves potential animal welfare threatening elements at different stages such as pick-up pens, loading, transport, unloading, lairage and race. At present no tool for assessing the welfare of finishing pigs from farm exit to stunning is available. The present study builds on a protocol for assessment of animal welfare of finishing pigs on the day of slaughter, a protocol which was based on the structure of the Welfare Quality® protocol for finishing pigs at an abattoir. The present study aimed to develop an animal welfare index (AWI) for the day of slaughter by aggregating 25 primarily animal-based measurements based on 38 experts opinion on inter-measurement and inter-stage weights. AWIs were calculated on animal level as the weighted sums of prevalence of the measurements, and were calculated for each of the six stages: pick-up pen, loading, transport, unloading, lairage and race (AWIStage) and across the stages (AWIOverall). The AWIs were tested in 5 farms including a total of 45 fattening pigs delivered to two Danish abattoirs. Possible inter-relations between the AWI and heart rate measurements were examined.For each welfare measurement within stage, significant differences between the mean expert scores were found. However, no difference between stage weights was found. Statistically significant differences in average heart rate between stages were found: 123a (pick up pen), 139b (loading), 120a (transport), 132d (unloading), 114c (lairage) and 134bd (race) bpm, respectively, (different letters indicate differences of P<0.05). No significant relationship between the score assigned by the expert panel per stage and the average heart rate within stage (r=0.61, P=0.19) or between AWIStage and heart rate (r=0.43, P=0.40) was found.In conclusion, this work has suggested a potential model for the aggregation of animal welfare measurements into animal welfare indexes for slaughter pigs on the day of slaughter. Further validation may allow simple comparison of the level of welfare between lorries, days, abattoirs etc. and may be used for future development of a feedback mechanism for optimization of the welfare of the pigs as well as for marketing.